Gastric metastasis of Merkel cell carcinoma, a rare cause of gastrointestinal bleeding: case report and review of the literature.

Merkel cell carcinoma (MCC) is a highly aggressive cutaneous tumor of neuroendocrine origin. It is usually seen in elderly Caucasian males and occurs in sun exposed areas of the body. Diagnosis of MCC can be challenging and requires confirmation by immunohistochemical studies.